JP2017166949A - Terrain variation determination method and terrain variation determination system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a terrain variation determination method capable of simply determining a variation state of a terrain without requiring a labor or cost.SOLUTION: The terrain variation determination method includes: a database preparation step of storing an observation object point in which a microwave reflection device array is installed, in association with coordinates; an observation SAR image database acquisition step (S101); an attention point selection step (S103); a coordinate acquisition step (S104) of referring to the database and acquiring coordinates of a selected attention point; a pixel specification step (S105) of specifying pixels in the observation SAR image data with respect to the acquired coordinates; a reflection intensity calculation step (S106) of calculating reflection intensities of the specified pixels; and a determination step (S107) of determining presence/absence of terrain variation at the attention point on the basis of the calculated reflection intensities.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a landform change determination method using a microwave reflection device array that reflects microwaves emitted from a flying object equipped with a synthetic aperture radar, and a landform change determination system that executes such a landform change determination method. .

  Synthetic Aperture Radar (SAR) mounted on ALOS2 and aircraft observes microwaves emitted from devices mounted on flying objects such as artificial satellites and aircraft and scattered near the surface of the earth. Is to investigate the state of Observed SAR image data acquired by the synthetic aperture radar is used for land classification (forest, cultivated land, water area, etc.) using the reflection intensity of the image pixel, and measurement of fluctuation amount by interference SAR using two-time data. .

For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2004-309178), a synthetic aperture interference process is performed on a ground-surface reflected wave of a pulsed radio wave emitted from one synthetic aperture radar 18 mounted on a flying object 16. In this method, the fluctuation amount of the ground surface is obtained by providing a tower-type base body 20 having a rigid structure on the ground surface 10 to be measured, and one of the radio wave reflectors 12a is reflected on the other side of the ascending orbit. The body 12b is installed so as to reflect the synthetic aperture radar radio wave on the descending orbit, and the reflected waves obtained twice each in the ascending orbit and descending orbit are subjected to the synthetic aperture interference process to obtain the ascending orbit. It is disclosed that the actual fluctuation amount from the past position of the measurement target point is calculated by obtaining the distance from the descending trajectory to the measurement target point and adding the conditions of the ground surface fluctuation direction specified by the ground structure. ing
JP 2004-309178 A

  If the terrain variation is to be obtained by the technique described in Patent Document 1, it is necessary to perform SAR observation a plurality of times in order to acquire interferometric SAR image data, and there is a problem that it takes time and effort. Furthermore, in the technique described in Patent Document 1, it is necessary to construct a tower-type base body having a rigid structure equipped with a radio wave reflector, which requires a large cost. Therefore, although it is suitable for precise measurement of the amount of movement of the ground surface, there is a problem that it is difficult to install widely on a wide mountain slope.

  The present invention solves the above-described problems, and the landform change determination method according to the present invention stores the observation target point on which the microwave reflection device array is installed and the coordinates of the point in association with each other. A database preparation step for preparing a database, an observation SAR image data acquisition step for acquiring observed SAR image data, a point of interest selection step for selecting a point of interest, and the database prepared in the database preparation step A coordinate acquisition step for acquiring the coordinates of the target point selected in the target point selection step, a pixel specifying step for specifying a pixel in the observed SAR image data with respect to the coordinates acquired in the coordinate acquisition step, and the pixel Of the pixel identified in the particular step And reflection intensity calculation step of calculating the elevation strength, based on the reflection intensity calculated by the reflected intensity calculating step, characterized by having a, a determining step of determining the presence or absence of terrain variations in the target point.

  In the terrain variation determination method according to the present invention, the microwave reflection device array includes a plurality of unit microwave reflection devices.

  The landform change determination method according to the present invention is characterized in that the microwave reflection device array appears as a pixel having a predetermined reflection intensity in the observed SAR image data.

  The terrain variation determination system according to the present invention is a terrain variation determination system that executes any one of the terrain variation determination methods described above.

  In the terrain variation determination method and the terrain variation determination system according to the present invention, a microwave reflection device array that can be widely installed on a wide mountain slope or the like is used, and it is not necessary to acquire interference SAR image data. Since the terrain variation can be determined immediately after acquiring the image data, according to the terrain variation determination method and the terrain variation determination system according to the present invention, due to a large-scale natural phenomenon such as a typhoon, heavy rain, and avalanche. Determine whether the landform change such as landslide has occurred, and where the landform change occurred such as landslide is quickly and easily without any effort, time and cost. It becomes possible.

It is a figure which shows an example of the computer which comprises the system which performs the landform change determination method which concerns on embodiment of this invention. It is a perspective view which shows an example of the unit microwave reflective device 1 used with the landform change determination method which concerns on embodiment of this invention. It is a figure which shows the preparation flow of the landform fluctuation | variation determination method which concerns on this invention. It is a figure which shows a mode that the some unit microwave reflection device 1 is arrange | positioned in the observation object point, and it was set as the microwave reflection device array 7. FIG. It is a figure which shows an example of the data structure of the database 40 used with the landform change determination method which concerns on embodiment of this invention. It is a figure which shows the flowchart of a terrain variation determination process. It is a figure which shows the data processing image in the flowchart of a terrain variation determination process. It is a figure which shows the state which the several unit microwave reflective device 1 installed in the observation object point A scattered by the landslide.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an example of a computer constituting a system for executing a landform change determination method according to an embodiment of the present invention.

  In FIG. 1, 10 is a system bus, 11 is a CPU (Central Processing Unit), 12 is a RAM (Random Access Memory), 13 is a ROM (Read Only Memory), 14 is a communication control unit that controls communication with an external information device, 15 is an input control unit such as a keyboard controller, 16 is an output control unit, 17 is an external storage device control unit, 18 is an input unit composed of input devices such as a keyboard, pointing device, and mouse, 19 is an output unit such as a printing device, Reference numeral 20 denotes an external storage device such as an HDD (Hard Disk Drive), 21 denotes a graphic control unit, and 22 denotes a display device.

  In FIG. 1, the CPU 11 retrieves and acquires data by communicating with an external device in accordance with a program ROM stored in the ROM 13 or a program stored in the large-capacity external storage device 20. Processing of output data in which graphics, images, characters, tables, etc. are mixed is executed, and management of a database stored in the external storage device 20 is further executed.

  Further, the CPU 11 comprehensively controls each device connected to the system bus 10. The program ROM in the ROM 13 or the external storage device 20 stores an operating system program (hereinafter referred to as OS) that is a basic program for controlling the CPU 11. The ROM 13 or the external storage device 20 stores various data used when performing output data processing or the like. The RAM 12 as a main memory functions as a main memory, work area, and the like for the CPU 11.

  The input control unit 15 controls the input unit 18 from a keyboard or a pointing device (not shown). The output control unit 16 performs output control of the output unit 19 such as a printer.

  The external storage device control unit 17 is an external storage device 20 such as an HDD (Hard Disk Drive) or a floppy disk (FD) that stores a boot program, various applications, font data, user files, editing files, printer drivers, and the like. Control access to. A system program for realizing the landform change determination method of the present invention is stored in the external storage device 20 as described above. The graphic control unit 21 is configured to perform drawing processing on information to be displayed on the display device 22.

  Further, the communication control unit 14 controls communication with an external device via a network, thereby acquiring data required by the system from a database held by an external device on the Internet or an intranet, It is configured to be able to send information to an external device.

  In addition to an operating system program (hereinafter referred to as OS) that is a control program for the CPU 11, the external storage device 20 is installed with a system program for operating the terrain variation determination system of the present invention on the CPU 11, data used in the system program, and the like. Saved and remembered.

  The data used in the system program for realizing the landform change determination method of the present invention is basically assumed to be stored in the external storage device 20, but in some cases, these data may be It is also possible to configure to acquire from an external device on the Internet or an intranet via the communication control unit 14. The data used in the system program for realizing the landform change determination method of the present invention can also be obtained from various media such as a USB memory, a CD, and a DVD.

  Next, the landform change determination method according to the present invention that can be executed by the computer configured as described above will be described in more detail.

  First, a microwave reflection device actually installed at a location to be observed in the landform change determination method according to the present invention will be described. The microwave reflection device reflects microwaves emitted from a synthetic aperture radar mounted on a flying object such as an artificial satellite or an aircraft.

  The microwave reflected by the microwave reflection device is reflected as a bright spot having a strength that does not normally occur in natural terrain in a part of the image of the observed SAR image data obtained by the synthetic aperture radar.

  In the landform change determination method according to the present invention, a microwave reflection device array 7 in which a plurality of unit microwave reflection devices 1 are arranged in an array is used as a microwave reflection device. By using a plurality of unit microwave reflection devices 1 as an array, the microwave reflection device array 7 has a predetermined reflection intensity that does not normally occur in natural terrain in observed SAR image data acquired by a synthetic aperture radar. Adjusted to appear as having pixels. The number of unit microwave reflection devices 1 constituting the microwave reflection device array 7 is as follows. The slope of the terrain (inclination angle) and the open space ratio (when the sky is 100) Adjust according to the proportion of the sky), the presence or absence of vegetation, the height of vegetation, etc.

  Here, in order to obtain a bright spot having stronger reflection intensity on the observed SAR image data, the size of the site where the microwave reflection device array 7 is installed is equal to or more than the ground resolution of the observed SAR image data. Smaller is preferable.

  Here, by using a plurality of unit microwave reflection devices 1 as an array, one or a plurality of unit microwave reflection devices 1 may become microwaves due to unforeseen reasons such as nests by living organisms or destruction by falling rocks Even if the loss of reflection capability occurs, it is possible to determine the presence or absence of terrain variation as long as it appears as a pixel having a predetermined reflection intensity that does not normally occur in natural terrain at the observation target point in the observed SAR image data.

  Here, even if one or several unit microwave reflection devices 1 in the array are lost, buried in the earth, or destroyed due to terrain fluctuation such as landslide, one or more unit microwave reflection devices If 1 remains, there is a high possibility that a pixel having sufficiently strong reflection intensity that does not normally occur in natural terrain in the observed SAR image data can be obtained. As a result, when a pixel having sufficiently strong reflection intensity that does not normally occur in natural terrain after terrain change is obtained, it is also possible to estimate the direction of terrain change and the amount of change in the horizontal direction.

  Here, in the landform change determination method according to the present invention, it is basically assumed that a plurality of unit microwave reflection devices 1 are used as the microwave reflection devices, but one unit microwave reflection device 1 is used. It can also be used. FIG. 2 shows an example of a microwave reflection device intended to reflect microwaves irradiated from all directions.

  FIG. 2 is a perspective view showing an example of the unit microwave reflection device 1 used in the landform change determination method according to the embodiment of the present invention. In the terrain variation determination method according to the present invention, other forms besides the unit microwave reflection device 1 shown in FIG. 2 can be used.

  The unit microwave reflection device 1 includes a plurality of reflection plates 3 made of a metal plate such as aluminum. The unit microwave reflecting device 1 has a shape in which eight corner reflectors having three reflecting surfaces are combined. That is, four three-surface corner reflectors that open in four directions are arranged above the unit microwave reflection device 1, and four three-surface corner reflectors that open in four directions below. It has a structure as arranged.

  A plurality of the unit microwave reflection devices 1 as described above are installed at a place to be observed so as to be placed on a base (not shown). The unit microwave reflection device 1 is also preferably reinforced by a reinforcing means (not shown). As such a reinforcing means, it is effective to provide a brace between the reflecting surface and the reflecting surface adjacent to the reflecting surface. It is also a preferable installation form to prevent the unit microwave reflection device 1 from being soiled by rain, soil, fallen leaves, living organisms' nest, etc., by a radome (cover) that transmits microwaves (not shown).

  Next, a process of preparing the landform change determination method according to the present invention by actually installing the unit microwave reflection device 1 as described above at a point to be observed will be described.

  FIG. 3 is a diagram showing a preparation flow of the landform change determination method according to the present invention. Such a preparation flow is executed manually.

  When the preparation flow of the landform change determination method according to the present invention is started in step S10 of FIG. 3, the process proceeds to step S20.

  In step S20, a step of installing the number of unit microwave reflection devices 1 that can obtain a reflection intensity equal to or higher than a predetermined value at the observation target point in at least one pixel of the observation SAR image data is performed. One feature of the landform change determination method according to the present invention is that a plurality of unit microwave reflection devices 1 are installed at an observation target point, and a microwave reflection device array 7 including these units is configured. .

  FIG. 4 is a diagram showing a state in which a plurality of unit microwave reflection devices 1 are arranged at the observation target point to form a microwave reflection device array 7. In the example of the observation target point illustrated in FIG. 4, a microwave reflection device array 7 including four unit microwave reflection devices 1 is disposed on a slope of a mountain. Here, the number of unit microwave reflection devices 1 for constituting the microwave reflection device array 7 is arbitrary. However, the microwave reflection device array 7 is the number of unit microwave reflection devices 1 such that the reflection intensity value of the microwaves is greater than or equal to a predetermined value in one pixel in the observed SAR image data acquired by the synthetic aperture radar. Configure.

  In step S30, it is determined whether or not the microwave reflection device array 7 has been installed for all observation points. If this judgment is NO, it will progress to Step S50 and will pay attention to the next observation object point. Then, it returns to step S10 and installation of the microwave reflection device array 7 is performed. On the other hand, if the determination in step S30 is YES, the process proceeds to step S40.

  In step S40, the database 40 that stores the observation target point and the latitude and longitude in association with each other is constructed. The longitude and latitude are measured by a GNSS (Global Navigation Satellite System), a total station, or the like. In addition, the following information that contributes to estimation of topographical changes may be added. For example, the number data of the unit microwave reflection devices 1 used to configure the microwave reflection device array 7, the inclination (tilt angle) of the terrain installed as various conditions of the observation target point, and the open space ratio (total The ratio of the sky when the sky is 100), the presence or absence of vegetation, and the type and height of vegetation with a high tree height covering the sky. FIG. 5 is a diagram showing an example of the data structure of such a database 40. In addition to the above, the microwave reflection device array 7 and observation target points are maintained and managed, such as the date of manufacture of the unit microwave reflection device, the manufacturer, the opening area of the corner reflector, and the observation results of the previous observation SAR image data. Useful information may be added to the database.

  In the example shown in FIG. 5, the example which installs the microwave reflective device array 7 in A, B, C, D, ... which are observation object points is shown. At each point, the GNSS data serving as coordinate data and the data of the number of unit microwave reflection devices 1 used to configure the microwave reflection device array 7 are associated and converted into data.

  In the present embodiment, coordinate data including latitude and longitude is used as GNSS data, but other reference coordinate data may be used. Further, the database 40 may store other data in association with each other, for example, data such as place names of points. In addition, the information on the related items mentioned in the description of step S40 can also be included.

  The database 40 prepared in step S40 is stored in the external storage device 20, and is used for the landform change determination process according to the present invention.

  In step S60, the preparation flow of the landform change determination method according to the present invention ends.

  Next, the terrain variation determination process according to the present invention, which is executed through the preparation flow as described above, will be described. FIG. 6 is a flowchart of the terrain variation determination process. Such a flowchart is executed by, for example, the computer shown in FIG.

  FIG. 7 is a diagram showing a data processing image in the flowchart of the landform change determination process. FIG. 7 illustrates data processing images in steps S103, S104, S105, and S106 when point A is selected as the point of interest.

  In FIG. 6, when the variation determination process is started in step S100, the process proceeds to step S101, and reading of observation SAR image data acquired by the synthetic aperture radar is executed. In the subsequent step S102, the database 40 is read.

In step S103, an individual point of interest for which the terrain variation determination process is to be performed is selected. (See Figure 7.)
In step S104, the coordinate data of the selected point of interest is acquired with reference to the database 40. In the subsequent step S105, the pixel in the observed SAR image data corresponding to the coordinate data is specified, and the next step In S106, the reflection intensity of the pixel is calculated. In calculating the reflection intensity of a pixel, it can be obtained by referring to the reflection intensity data of the pixel. (See Figure 7 for all steps.)
Here, in step S105, in order to consider the error (pixel position deviation) of the observed SAR image data itself, it exists within a range of about 5 pixels in radius with the coordinate data of the point of interest acquired in step S104 as the center. Calculate the reflection intensity of all pixels. The setting of the range for calculating the reflection intensity is adjusted according to the ground resolution and performance of the observation SAR image to be used. The reflection intensity is calculated by comparing the coordinates of the observation point with the coordinates of the observation point obtained from the observed SAR image data on the SAR observation day where it is clear that topographic changes such as heavy rain, landslides, and avalanches have not occurred. The reference value of the range to be obtained is obtained.

  In step S107, it is determined whether or not the calculated reflection intensity is greater than or equal to a predetermined value.

  When the determination result in step S107 is YES, it is considered that the microwave reflection device array 7 is not changed from the initial setting, so the process proceeds to step S110, and it is determined that there is no landform change at the point of interest.

  On the other hand, when the determination result in step S107 is NO, it is considered that the microwave reflecting device array 7 has undergone some change from the initial installation stage, and therefore, the process proceeds to step S108, where it is determined that there is a landform change at the point of interest. To do. When it is determined that there is a terrain variation at the point of interest, the observed SAR image data of the point is displayed as a graphic, printed by the output device (output unit 19), or by the communication device (communication control unit 14). Can be notified.

  FIG. 8 is a diagram illustrating a state in which a plurality of unit microwave reflection devices 1 installed at the observation target point A are scattered due to a terrain change such as a landslide. When the individual unit microwave reflection devices 1 constituting the microwave reflection device array 7 are in a state as shown in FIG. 8, it becomes impossible to obtain a predetermined reflection intensity at the corresponding pixel in the observed SAR image data. Thereby, it is possible to perform the determination as in step S108. Although not shown, even if the unit microwave reflection device 1 is buried, destroyed, or lost due to a terrain change such as a landslide, it is determined at a predetermined pixel in the observed SAR image data as in the state of FIG. The reflection intensity cannot be obtained.

  In step S109, it is determined whether or not processing has been executed for all the points of interest. When the determination in step S109 is NO, the process proceeds to step S111, the next point of interest is selected, and the process returns to step S104. On the other hand, when the determination in step S109 is YES, the process proceeds to step S112 to end the variation determination process.

  As described above, in the terrain variation determination method and the terrain variation determination system according to the present invention, the microwave reflection device array 7 that can be widely installed on a wide mountain slope is used, and there is no need to acquire interference SAR image data. Since the terrain variation can be determined immediately after the observation SAR image data is acquired, according to the terrain variation determination method and the terrain variation determination system according to the present invention, a large-scale such as typhoon, heavy rain, avalanche, etc. Whether or not landslides or other terrain changes have occurred due to natural phenomena, and where the landslide or other terrain changes have occurred, the state of terrain changes quickly and easily without any effort, time, or cost. Can be determined.

DESCRIPTION OF SYMBOLS 1 ... Unit Microwave reflection device 3 ... Reflector 7 ... Microwave reflection device array 10 ... System bus 11 ... CPU (Central Processing Unit)
12 ... RAM (Random Access Memory)
13 ... ROM (Read Only Memory)
DESCRIPTION OF SYMBOLS 14 ... Communication control part 15 ... Input control part 16 ... Output control part 17 ... External storage device control part 18 ... Input part 19 ... Output part 20 ... External storage device 21 ... Graphic control unit 22 ... Display device 40 ... Database

Claims (4)

A database preparation step of preparing a database for storing the observation target point where the microwave reflection device array is installed and the coordinates of the point in association with each other;
An observation SAR image data acquisition step of acquiring observed SAR image data;
A point of interest selection step for selecting a point of interest;
A coordinate acquisition step of referring to the database prepared in the database preparation step and acquiring the coordinates of the target point selected in the target point selection step;
A pixel specifying step of specifying a pixel in the observed SAR image data with respect to the coordinates acquired in the coordinate acquiring step;
A reflection intensity calculating step of calculating the reflection intensity of the pixel specified in the pixel specifying step;
Based on the reflection intensity calculated in the reflection intensity calculation step, a determination step for determining the presence or absence of terrain fluctuation at the point of interest;
A method for determining terrain variation, comprising: The terrain fluctuation determination method according to claim 1, wherein the microwave reflection device array includes a plurality of unit microwave reflection devices. The landform change determination method according to claim 1 or 2, wherein the microwave reflection device array appears as a pixel having a predetermined reflection intensity in the observed SAR image data. A terrain variation determination system for executing the terrain variation determination method according to any one of claims 1 to 3.

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